The majority of the broccoli grown in the United States is grown in California and Arizona. Of the estimated 3 billion pounds of broccoli that are marketed in the United States each year, about 1 billion pounds are minimally processed soon after harvest and are shipped fresh, ready for consumption. The fresh broccoli market in the United States consists of two segments: (1) whole broccoli crowns and bunch broccoli (about 700 million pounds yearly) and (2) broccoli florets (about 300 million pounds yearly). A broccoli crown is a single 4 or 5 inch stalk, typically of the Marathon variety, with lateral stems trimmed off. The head of a broccoli crown is typically a very even mushroom shape and tightly packed flower buds, which are ideally deep green in color, tight and consistent. Bunch broccoli is a group of broccoli stalks, typically of the Arcadia variety, with lateral stalks trimmed off, which are held together with a rubber band or twist tie. Florets are broccoli buds that have been trimmed from a stalk. About 280 million pounds of the broccoli crowns and bunch broccoli market are shipped within the United States each year, and about 420 million pounds are exported The floret market is primarily within the United States. About 300 million pounds of florets are shipped to food service providers and retailers each year.
Quality aspects that are among the most prized in fresh broccoli is a deep green color, dense and compact heads, tight flowers, few laterals, and minimal cut end darkening. While whole, unprocessed broccoli may be stored under refrigeration for many weeks without significant deterioration, minimally processed fresh broccoli that has been in refrigerated storage for as little as a week will become pale green, the florets will begin to turn yellow, and the cut ends will begin to brown.
The rate at which deterioration of minimally processed fresh broccoli occurs is also a function of the physiological condition of the broccoli prior to the harvesting and processing, the chemical treatments that are applied to the broccoli during processing, if any, and the humidity levels and the temperatures at which the fresh broccoli is stored. For example, florets are washed and cooled in chlorinated water. This is the only chemical treatment in use today. Variations in the physiology of the whole, unprocessed heads of broccoli caused by different degrees of environmental stress during the growing season, such as heat stress and drought stress, will also result in variations in the onset of deterioration when the broccoli is processed and stored under a given set of storage conditions. Broccoli that is grown in poorly irrigated fields tends to degrade more rapidly after processing than does broccoli that is grown in well-irrigated fields, for example.
In addition, broccoli has a very high respiration rate that results in the generation of heat. This heat of respiration can contribute to the rate of deterioration of the broccoli during shipment, especially in the center portions of the typical box of fresh broccoli crowns, bunch broccoli or florets, or in the center of a pallet.
Color deterioration of broccoli is unsightly and unappetizing. As a result, consumers invariably associate discoloration with distastefully old broccoli, even though the taste and nutritional value of the fresh broccoli are not affected by the appearance of discoloration. Therefore, the appearance of discoloration leads to significant commercial waste if the processed fresh broccoli is discarded before taste and nutrition are affected.
To date the discoloration and other aspects of deterioration of minimally processed fresh broccoli, and the contributing heat of respiration, have been controlled primarily by packing and shipping freshly harvested broccoli in ice. Many broccoli processors and shippers place minimally processed fresh broccoli in water-resistant, shipping boxes containing about twenty to twenty-four pounds of broccoli crowns or about forty pounds of broccoli florets and then cover the broccoli with ice. The costs of water-resistant boxes and ice, as well as the additional shipping weight added by the ice packing, results in significant added costs for shipping fresh, minimally processed broccoli from the field to the market.